CEM 2018 - Abstract

Field validation of a novel, near real-time methane fugitive monitoring system for vent and leak detection

Abstract Type:

Seminar

Session Choice:

Fence line monitoring & measurement of fugitive/diffuse emissions

Presenter Name:

Mr David Butterfield

Co-authors:

Mr Matt Williams

Company/Organisation:

National Physical Laboratory

Country:

United Kingdom

Abstract Information :

National Grid Plc is incentivised by the Office of Gas and Electricity Markets (Ofgem) to conduct research into new techniques to enable National Grid Gas (NGG) to improve understanding and transparency, and allow for cost-effective mitigation, of greenhouse gas (GHG) venting on the National Transmission System (NTS). The mechanism by which this is done is special condition 8J of the Gas Transporters Licence, the Greenhouse Gas Investigation Mechanism (GHGIM).

Since 2008 NGG has conducted 4 yearly fugitive emission surveys of ground level accessible valves and pipework on all 23 compressor stations and terminals of the National Transmission System (NTS). However, these surveys only provide a 'snap-shot' of emissions and are limited to accessible pipework not including pits and vents. In addition, long term boundary fence-line methane monitoring cannot be used to locate sources of emissions.

The aim of this project was to develop a cost effective methodology to enable NGG to monitor and control fugitive emissions from above ground installations (AGI) on the National Transmissions System (NTS), and to understand both planned and unplanned venting events. The project involved trialling a method to assess the practicality, performance and cost effectiveness of the approach. In addition there was a validation of the "portability" of the equipment to expand application beyond AGIs.

The technique trialled was the use of a highly accurate and sensitive real-time methane gas analyser to monitor at an array of sample points from locations around the boundary fence of an AGI. These measurements combined with a continuously updated reverse dispersion model provided hourly mass emission measurements for the facility. The results of the reverse dispersion model provided a focus for operational staff on the installation to investigate the detected leaks through physical inspection of the highlighted area and sniffing techniques. Where available optical gas imaging (OGI) was used and leaks quantified using high-flow samplers in order to prioritise leak repair.

Results of the project will be shown demonstrating how the fugitive monitoring system identified and quantified fugitive leaks from 2 AGI locations.